The Ultra Mobile Broadband (UMB) session release operation resulted from packet data session release in the UMB access network comprises the procedure as shown in FIG. 1. For an Access Terminal (AT) in an active status, when an Access Gateway (AGW) releases packet data session, it sends a Proxy Mobile IP (PMIP) registration revocation message to a Data Attachment Point (DAP) which notifies a Session Reference Network Controller (SRNC) that the packet data session has been released. This may cause the SRNC to decide to release the air interface session with the AT. After releasing the air interface session, the SRNC sends a single session release message to notify all the Evolved Base Stations (eBSs) in the route set that the session has been released. The eBSs send confirmation messages to confirm the reception of the session release message. In this releasing procedure, it is assumed that there is a PMIP tunnel only between the DAP and the AGW. But in fact, any eBS in the route set of the AT in the access network may have one reverse PMIP tunnel to the AGW. Therefore, the case of multiple PMIP tunnels should be considered in the UMB session release procedure resulted from the packet data session release, to improve the procedure of the session release.
It is noted that in the UMB, each AT has one route set, the members of the route set are a set of access route instances, because there is a route instance between each SRNC or eBS and an AT respectively. Therefore, the route set members of the AT are SRNC and eBS.